High power density fuel cell stack using micro structured components

ABSTRACT

The invention is a multiple fuel cell layer structure with numerous fuel cell layers, each fuel cell has an anode, a cathode, a positive end and a negative end, wherein a first fuel cell layer is stacked on top of a second fuel cell layer such that the anode side of the first fuel cell and the anode side of the second fuel cell adjoin, additional fuel cell layers can then be added in a like manner, at least one seal disposed between the adjacent fuel cell layers forming at least one plenum, and a positive and a negative connector is connected to the stack to an outside load such that when fuel is presented to the anode sides of the fuel cell layers and oxidant is presented to the cathode sides of the fuel cell layers current is produced to drive the outside load.

BACKGROUND OF THE INVENTION

The application herein claims priority from the provisional PatentApplication 60/360,638 with a filing date of Mar. 1, 2002.

FIELD OF THE INVENTION

The present invention relates to fuel cells. More specifically theinvention relates to methods of combining separate fuel cell layers toform a fuel cell layer structure.

High power density fuel cells have long been desired.

Existing fuel cells generally are a stacked assembly of individual fuelcells, with each cell producing high current at low voltage. The typicalcell construction involves reactant distribution and current collectiondevices brought into contact with a layered electrochemical assemblyconsisting of a gas diffusion layer, a first catalyst layer, anelectrolyte layer, a second catalyst layer and a second gas diffusionlayer. With the exception of high temperature fuel cells, such as moltencarbonate cells, most proton exchange membrane, direct methanol, solidoxide or alkaline fuel cells have a layered planar structure where thelayers are first formed as distinct components and then assembled into afunctional fuel cell stack by placing the layers in contact with eachother.

One major problem with the layered planar structure fuel cell has beenthat the layers must be held in intimate electrical contact with eachother, which if intimate contact does not occur the internal resistanceof the stack increases, which decreases the overall efficiency of thefuel cell.

A second problem with the layered planar structured fuel cell has beento maintain consistent contact between the layers for sealing andensuring correct flows of reactants and coolants in the inner recessesof the layer structured fuel cell. Also if the overall area of the cellbecomes too large then there are difficulties creating the contactingforces needed to maintain the correct fluid flow distribution ofreactant gases over the electrolyte surface.

Existing devices also have the feature that, with the layered planarstructure fuel cell since both fuel and oxidant are required to flowwithin the plane of the layered planar structured fuel cell, at least 4and up to 10 but typically 8 distinct layers have been required to forma workable cell, typically a first flowfield, a first gas diffusionlayer, a first catalyst layer, a first electrolyte layer, a secondcatalyst layer, a second gas diffusion layer, a second flowfield layerand a separator. These layers are usually manufactured into separatefuel cell components and then the layers are brought into contact witheach other to form a fuel cell stack. When contacting the layers caremust be taken to allow gas diffusion within the layers while preventinggas leaking from the assembled fuel cell stack. Furthermore, allelectrical current produced by the fuel cells in the stack must passthrough each layer in the stack, relying on the simple contacting ofdistinct layers to provide an electrically conductive path. As a result,both sealing and conductivity require the assembled stack to be clampedtogether with significant force in order to activate perimeter seals andreduce internal contact resistance.

The manufacture of the layers for existing fuel cell configurations isoften expensive and difficult. The bipolar plates, which serve asoxidant and fuel flowfields as well as the separator are oftenconstructed from graphite which is difficult to machine, addingsignificant cost to the fuel cell stack. The membrane electrode assembly(MEA) is usually constructed by first coating a solid polymerelectrolyte with catalyst on either side and then pressing gas diffusionelectrodes onto the electrolyte. The fuel cell assembly requiresmultiple individual bipolar plates and membrane electrode assemblies tobe connected together in a serial manner. Usually discrete seals must beattached between neighbouring bipolar plates and membrane electrodeassemblies and the whole stack of sealed bipolar and MEA layers must beheld together under considerable compressive force.

A need has existed to develop alternative fuel cell designs that do notperpetuate the approach of assembling discrete layers in a serialmanner. One way to meet this need is to build fuel cells using amicro-structured approach wherein micro-fabrication techniques andnano-structured materials can be combined to create novel devices notsubject to the problems commonly associated with conventional fuel celldesigns. The application of micro-scale techniques to fuel cells has anumber of distinct advantages. Specifically, the potential for increasedpower density due to thinner layers and novel geometries, improved heatand mass transfer, improved and/or more precise catalyst utilization andreduced losses with shorter conductive path lengths will all make fuelcells more efficient and enable higher volumetric power densities. Theopportunity to include ancillary systems into the fuel cell design andthe potential for new applications to emerge present even more potentialbenefits.

A need has existed for a micro fuel cell capable of low costmanufacturing because of having fewer parts than the layered planarstructure fuel cell.

A need has existed for a micro fuel cell having the ability to utilize awide variety of electrolytes.

A need has existed for a micro fuel cell, which has substantiallyreduced contact resistance within the fuel cell.

A number of prior inventions have used microscale-manufacturingtechniques with fuel cells. U.S. Pat. No. 5,861,221 presents a ‘membranestrip’ containing a number of conventional MEAs connected to each otherin series by connecting the edge of the negative electrode of one MEA tothe edge of the positive electrode of the next MEA. Two configurationsare considered. The first constructs the ‘membrane strip’ by placing theMEAs together in a step-like configuration. The second constructs the‘membrane strip’ by combining MEAs end-to-end with electricallyconductive regions between them that connect the cells in series. Insome follow-up work (U.S. Pat. No. 5,925,477) the same inventorsincorporate a shunt between the electrodes to improve the electricalconductivity of the cell. The MEAs themselves are of conventionallayered structure design, and the overall edge collected assemblycontinues to rely on conventional seals between neighbouring MEAs.

U.S. Pat. No. 5,631,099 and U.S. Pat. No. 5,759,721 use similar seriesconnection concepts but apply a number of other micro-scale techniquesto the fuel cell design. By doing so multiple fuel cells are formedwithin a single structure simultaneously. The fuel cells themselvesstill reside as layered planar devices mounted onto a carrier, withinterconnection between neighbouring fuel cells requiring a penetrationof the carrier layer. Most of the techniques discussed in these patentsrelate to the creation of methanol tolerant catalysts and theapplication of palladium layers to the catalyst to prevent methanolcrossover within the cells.

WO 01/95406 describes a single membrane device that is segmented tocreate multiple MEA structures. Complex bipolar plates that aredifficult to manufacture provide both fuel and oxidants to both sides ofthe MEA layer. U.S. Pat. No. 6,127,058 describes a similar structure,but instead of complex manifolding of reactant gases, only one reactantis supplied to either side of the MEA layer. Series interconnection ofthe fuel cells formed within the single MEA layer is achieved throughexternal current collectors arranged around the perimeter of the deviceproviding electrical connection from the top of the MEA layer to thebottom of the MEA layer. Such perimeter electrical connections areinefficient.

Some prior art fuel cells attempt to reduce size and fabrication costsby applying micro-fabrication techniques. For example the Case WesternReserve University device forms multiple fuel cells on a carriersubstrate using thin layer processes similar to those used in printingand semi-conductor fabrication (Wainwright et al. “A micro-fabricatedHydrogen/Air Fuel Cell” 195 Meeting of the Electrochemical Society,Seattle, Wash.; 1999). In these designs the fuel cells remain ofconventional planar design, with the exception that the fuel cells arebuilt-up to a base substrate. The cathodes must be formed on top of theplanar electrolytes and then must be connected to neighbouring anodeswith an explicit interconnect.

All the cells presented above use current collection on the edge of theelectrode. This significantly increases the internal cell resistance ofthese cells. Each of these cells are also based on solid polymerelectrolytes as this is the only electrolyte that allows for easymanufacture. Furthermore, all of the cells presented above achieve amicro fuel cell design by forming multiple fuel cells within a singleelectrolyte plane.

The concept of using non-planar electrolytes has been considered in thepast. GB 2,339,058 presents a fuel cell with an undulating electrolytelayer. In this configuration a conventional layered MEA is constructedin an undulating fashion. This MEA is placed between bipolar plates.This design increases the active area that can be packed into a givenvolume. However, this design still relies on the expensive andcomplicated layered structure with explicit seals and requirescompressive force to maintain internal electrical contact and sealing.JP 50903/1996 presents a solid polymer fuel cell having generally planarseparators with alternating protruding parts serving to clamp a powergeneration element (apparently an MEA) into a non-planar but piecewiselinear shape. As with GB 2,339,058, this document continues to rely onthe expensive and complicated layered structure but this design alsoputs undue stress on the MEA by forcing it into a non-planar arrangementusing the separator plates.

In addition to non-planar designs, some prior art presents tubularconfigurations. U.S. Pat. No. 6,060,188 presents a cylindrical fuel cellwith a single MEA layer formed into a cylinder. Fuel or oxidant isdelivered to the interior recess of the cylinder with the other reactantdelivered on the exterior. Within this design, each cylindricalstructure creates a single cell, with current flowing through theannular cylindrical wall that is the fuel cell. A method of providingseries electrical interconnection between fuel cells or of sealingindividual fuel cells is not disclosed. This design is reminescent oftubular designs for solid oxide fuel cells that are well known.

U.S. Pat. Nos. 5,252,410 and 4,037,023 and JP 6-3116369 present designsthat form flow channels directly into the porous carbon gas diffusionelectrode layers of the MEA. This approach does not get away from theessentially planar structure of the MEA or the flow field and separatorplate but rather puts the gas distribution layer into the GDE ratherthan into the separator plate. Although this can decrease the cost thefinal structure is still a conventional layered structure fuel cell witha simple rearrangement of the layers. The ability to form flow fieldsinto the fuel cell layer structure and create a fuel cell without theneed for separator between layers is not discussed.

A need has existed to develop fuel cell topologies or fuel cellarchitectures that allow increased active areas to be included in thesame volume, i.e. higher density of active areas. This will allow fuelcells to be optimized in a manner different than being pursued by mostfuel cell developers today.

SUMMARY OF THE INVENTION

The present invention relates to methods of combining separate fuel celllayers to form a fuel cell layer structure. A number of features of thefuel cell layers are unique and allow for much simpler stackingstructures.

More specifically, the present invention contemplates a multiple fuelcell structures with a plurality of fuel cell layers, each fuel celllayer comprising an anode side and a cathode side, a positive end and anegative end. The first fuel cell layer is stacked on top of a secondfuel cell layer such that the anode side of the first fuel cell layerand the anode side of the second fuel cell layer adjoin. Additional fuelcells layers can then be disposed on the fuel cell layers in a likemanner. The invention also has at least one seal disposed between theadjacent fuel cell layers forming at least one plenum and a positiveconnector and a negative connector for connecting the stack to theoutside load. When fuel is presented to the anode sides of the pluralityof fuel cell layers and oxidant is presented to the cathode sides of theplurality of fuel cell layers, a current is produced to drive theoutside load.

In this embodiment optional formed flow fields can be created on thefuel cell layers. Alternately, the at least one plenum created by the atleast one seal can be solid with a flow field. The plenum can alsocomprise a permeable material. The fuel cell layers of the multiple fuelcell structure can be connected in series, in parallel, or incombinations thereof between the positive and negative electricalconnectors.

This configuration achieves the functionality of a conventional stackstructure without the requirement for any explicit multi-function orbipolar separator plate to be inserted between discrete fuel cells orfuel cell layers resulting in an overall more space and materialefficient design. Furthermore, since there is no current flow betweenneighbouring fuel cell layers the task of sealing and connecting thefuel cell layers into the stack is simplified considerably. Forming theflow fields on the surface of the fuel cell layers allows the reactantdistribution flow paths to be formed without significantly decreasingthe total reactive area of the fuel cell stack in comparison to anembodiment constructed without the formed flow fields.

The invention further contemplates a bi-level fuel cell layer structurecomprising: a first fuel cell layer and a second fuel cell layer, eachfuel cell layer comprising an anode side and a cathode side, a positiveend and a negative end, and wherein the first fuel cell layer is stackedon top of the second fuel cell layer such that the anode side of thefirst fuel cell layer and the anode side of the second fuel cell layeradjoin forming a bi-level stack; a seal disposed between the first andsecond fuel cell layers forming a fuel plenum; a positive connector forconnecting the bi-level stack to an outside load; and a negativeconnector for connecting the bi-level stack to the outside load; suchthat when fuel is introduced to the fuel plenum and the cathode sidesare exposed to an oxidant, current is produced to drive the outsideload.

The individual fuel cell layers in the bi-level fuel cell layerstructure can be connected in either parallel or in series. Theresulting structure is an enclosed plenum air breathing fuel cell thatachieves a series electrical connection of the individual fuel cells ineach fuel cell layer. Only fuel is required to be fed to the interior ofthe structure and electrical current flows within the two fuel celllayers independently of one another. There is no electrical connectionbetween the two fuel cell layers except at the positive and negativeelectrical connections at either end of the fuel cell layers in thestructure.

An optional solid material with a flow field can be disposed in theplenum created by the first and second fuel cell layers and the seal.The plenum could also comprise a permeable material or a hydrogenstorage material. Alternately pressurized hydrogen or a liquid fuelcould be stored within the plenum. It is also envisioned that the plenumbe open to the ambient environment.

The fuel cell layers within the bi-level fuel cell structure can alsocomprise formed flow fields for the controlled delivery of reactantgases to the layers.

BRIEF DESCRIPTION OF THE FIGURES

A specific embodiment of the invention will be described by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a first embodiment of the inventivefuel cell;

FIG. 1a is a cross-sectional detailed view of the anode with thecatalyst at a first depth in the porous substrate;

FIG. 1b is a cross sectional detailed view of the anode with thecatalyst at a second depth in the porous substrate;

FIG. 1c is a cross sectional detailed view of the cathode;

FIG. 2 is a cross-sectional view of a dead ended embodiment of theinventive fuel cell;

FIG. 2a is embodiment of the fuel cell according to the invention withthe fuel and oxidant plenums being solid with flow channels containedtherein;

FIG. 3 is a cross-sectional view of another embodiment of a dead endedfuel cell;

FIG. 3a is an embodiment of the invention with an oxidant plenum open tothe ambient environment;

FIG. 3b is an embodiment of the invention with a fuel plenum open to theambient environment;

FIG. 4 is a cross-sectional view of a fuel cell layer formed bycombining multiple fuel cells of the type described in FIG. 1;

FIG. 4a is a cross sectional view of a multiple porous substrate fuelcell layer with the fuel plenum open to the ambient environment;

FIG. 4b is a cross sectional view of a multiple porous substrate fuelcell layer with the oxidant plenum open to the ambient environment;

FIG. 4c is a cross sectional view of a fuel cell layer with up to 5000fuel cells;

FIG. 5 is a cross-sectional view of a fuel cell with multiple fuel cellsof the type described in FIG. 1 formed within a single substrate;

FIG. 5a is another embodiment of a fuel cell with multiple cells;

FIG. 6 is a perspective view of a fuel cell layer containing multiplefuel cells of the type described in FIG. 1;

FIG. 7 is another detailed perspective view of the fuel cell of theinvention with undulating channels;

FIG. 8 is a perspective view of a cylindrical version of a fuel cellaccording to the invention;

FIG. 8a is a cross-sectional view of an embodiment of the fuel cell ofFIG. 1 in which the substrate is irregularly shaped;

FIG. 9 is a cross sectional view of a cylindrical version of a fuel cellaccording to the invention;

FIG. 10 is another embodiment of the inventive fuel cell of theinvention with the channels in the form of a set of stacked annularrings;

FIG. 11 is another embodiment of the inventive fuel cell with thechannels in the form of a spiral around the cylinder; and

FIG. 12 is a perspective view of a bi-level fuel layer structure;

FIG. 12a is a perspective view of another bi-level fuel cell layerstructure;

FIG. 13 is an exploded perspective view of a bi-level fuel cell layerstructure with formed flowfields;

FIG. 14 is a cross-sectional view of yet another bi-level fuel cellstructure;

FIG. 15 is a perspective view of a multiple fuel cell layer structure;and

FIG. 15a is a perspective view of another multiple fuel cell layerstructure.

DETAILED DESCRIPTION OF INVENTION

The present invention relates to a microstructure fuel cell having asubstrate, which is preferably porous, an assembly of fuel cells havinga single or multiple substrate structure and methods for manufacturingsuch fuel cells and fuel cell layers.

The invention relates to a specific fuel cell architecture that is of anintegrated design in which the functions of gas diffusion layers,catalyst layers, and electrolyte layers are integrated into a singlesubstrate. This architecture makes it possible to fold together thevarious ‘layers’ of which a working fuel cell is formed and producelinear, curvilinear, undulating or even fractal shaped electrolyte pathsthat allow for higher volumetric power density to be achieved byincreasing the electrochemically active surface area. In addition, byforming the various fuel cell layers within a single substrate theproblem of simple contacting of fuel cell components to createelectrical connections is eliminated, thus creating the potential forlower internal cell resistances to be achieved. The cell layersthemselves can be constructed in planar, non-planar or involuteconfigurations providing further advantages in increasing surfaces areasand providing flexibility in applications. This integrated designenables simpler manufacturing processes and scaling of the design.

Unlike existing fuel cell designs, the present invention, in oneembodiment, provides convoluted electrolyte layers, which do notsmoothly undulate. Other embodiments of the invention include shapesthat are essentially non-smooth. Utilizing such non-smooth electrolytepaths allows for greater overall surface areas for the fuel cellreactions to be packed into a given volume that can be achieved whenplanar electrolyte layers are employed as in conventional fuel celldesigns. The present invention also allows for significantly decreaseddistances between separate electrolyte layers, thereby allow for agreater surface area in a given volume than conventional designs.

The present invention contemplates the use of a design inspired byfractal patterns, which provides long electrolyte path lengths. Theinvention includes a method for building fuel cells and “stacks” thatare not dependent on the layered process and which do not require thepost-manufacturing assembly of distinct layered components. Theconventional relationship between MEA layers and bipolar plates iseliminated, as is the reliance on multiple discrete layered structures.The invention also contemplates a design with individual fuel cellsturned on their side relative to the overall footprint of the assembledfuel cell device. The invention contemplates building multiple fuelcells with an integrated structure on a single substrate using parallelmanufacturing methods.

Specifically, it is contemplated to use a porous substrate for the fuelcell through which reactant gas will diffuse with little driving force.The substrate may or may not be electrically conductive. If it isconductive, it is contemplated to insulate at least a portion of thesubstrate, which typically would separate the anode from the cathode,this insulation may be formed by the electrolyte separating the anodefrom the cathode and, if necessary, an optional insulating structuralmember may be added. More specifically, the fuel cell is contemplated tohave: (a) a fuel plenum comprising fuel; (b) an oxidant plenumcomprising oxidant; (c) a porous substrate communicating with the fuelplenum, and the oxidant plenum further comprising a top, a bottom, afirst side, and a second side; (d) a channel formed using the poroussubstrate, wherein the channel comprises a first channel wall and asecond channel wall; (e) an anode formed from a first catalyst layerdisposed on the porous substrate of the first channel wall; (f) acathode formed from a second catalyst layer disposed on the poroussubstrate of the second channel wall; (g) electrolyte disposed in atleast a portion of the channel contacting the anode and the cathodepreventing transfer of fuel to the cathode and preventing transfer ofoxidant to the anode; (h) a first coating disposed on at least a portionof the porous substrate to prevent fuel from entering at least a portionof the porous membrane; (i) a second coating disposed on at least aportion of the porous substrate to prevent oxidant from entering atleast a portion of the porous substrate; (j) a first sealant barrierdisposed on the first side and the second sealant barrier disposed onthe second side; (k) a positive electrical connection disposed on thefirst side; (l) a negative electrical connection disposed on the secondside; and wherein the resulting fuel cell generates current to drive anexternal load.

Referring to FIG. 1, which is a cross-sectional view of one embodimentof the invention, a fuel cell 8 has an optional fuel plenum 10containing fuel 11. A porous substrate 12 is adjacent the optional fuelplenum 10. The fuel plenum can have an optional fuel plenum inlet 18.The fuel plenum can also have an optional fuel plenum outlet 20. Anoptional oxidant plenum 16 containing oxidant 13 is adjacent the poroussubstrate 12. The oxidant plenum can have an optional oxidant plenuminlet 52. The oxidant plenum can also have an optional oxidant plenumoutlet 54. If no oxidant plenum is used the fuel cell uses the ambientenvironment as a source of oxidant.

The porous substrate 12 can have a shape that is rectangular, square ororthogonal or alternatively, it can be irregularly shaped. In thisembodiment it is pictured as being formed within a single plane,although non-planar substrates or multiple substrate configurations areenvisioned.

A channel 14, formed using the porous substrate, can be straight or ofarbitrary design. If of arbitrary design the channel is referred tothroughout this application is “undulating.” If multiple channels arepresent at least one may be undulating. The channel 14 has a firstchannel wall 22 and a second channel wall 24. Additionally the poroussubstrate 12 has a top 100, bottom 102, first side 104 and a second side106.

The channel can comprise an undulating channel, a straight channel or anirregular channel. If undulating, the channel can be sinusoidal in shapeand if undulating, the channel may be of a shape that is in at leastthree planes.

An anode 28 is created on or alternately in the surface of the firstchannel wall 22, although the anode could be embedded in the wall aswell. Anode 28 is created using a first catalyst layer 38 on or into thesurface of the first channel wall 22.

A cathode 30 is formed on the surface or alternately in the secondchannel wall 24. Like the anode 28, the cathode 30 could be embedded inthe second channel wall 24. Cathode 30 is created using a secondcatalyst layer 40.

FIGS. 1a, 1b and 1c provide details of the cathode and anode of the fuelcell. FIG. 1a shows the anode 28 at a first depth within the poroussubstrate 12, FIG. 1b shows the anode 28 at a second depth within theporous substrate 12 and FIG. 1c shows the cathode 30.

The catalyst layers can be deposited on the first and channel walls orcan be formed in the channel walls. In one embodiment the first andsecond catalyst layers are disposed in the porous substrate to at leasta minimum depth to cause catalytic activity.

Referring back to FIG. 1, an electrolyte 32 is disposed in the channel14.

A first coating 34 is disposed on at least a portion of the poroussubstrate 12 preventing fuel from entering at least a portion of theporous substrate 12. A second coating 36 is disposed on at least aportion of the porous substrate 12 preventing oxidant from entering atleast a portion of the porous substrate 12.

A first sealant barrier 44 is disposed on the first side of the poroussubstrate and a second sealant barrier 46 is disposed on the second sideof the porous substrate. The sealant barriers can optionally be disposedwithin a sealant barrier channel 43.

A positive electrical connection 50 is engaged with the porous substrate12 on the first side of the porous substrate.

A negative electrical connection 48 is engaged with the porous substrate12 on the second side of the porous substrate.

The resulting fuel cell generates current 56 to drive an external load58.

FIG. 2 is another embodiment of the invention showing a dead endedversion of the fuel cell 108 specifically excluding the fuel outlet 20and the oxidant outlet 54 of the FIG. 1 embodiment.

In one version of this embodiment of the invention, it is contemplatedthat the electrolyte 32 can be mounted in the channel 14 at an angle 76,preferably at an angle, which is perpendicular to the longitudinal orhorizontal axis 74 of the predominant portion of the porous substrate12.

In FIG. 2 an optional support member 26 separates first channel wall 22from second channel wall 24 however the support member is not requiredin every embodiment. Some alternatives envision multiple support membersas shown in FIG. 2a. Between one and 50, or more support members arecontemplated herein.

Now referring to FIG. 2a, a fuel cell is shown with a solid fuel plenum10 with flow fields 126 and a solid oxidant plenum 16 with flow fields126. It is also envisioned that the fuel plenum comprises a permeablematerial containing the fuel. The oxidant plenum can also comprise apermeable material. It is understood that the fuel plenum and oxidantplenum need not be constructed in the same manner and a variety ofcombinations of oxidant and fuel plenum configurations can be used. Thefuel plenum and the oxidant plenum can each have a variety of shapes,round, elliptoid, rectangular or square. It is particularly contemplatedthat the fuel plenum has a rectangular cross-section.

FIG. 3 is a cross-section of another embodiment of a dead ended versionof the fuel 110 that excludes the fuel inlet 18 and the fuel outlet 20as well as the oxidant inlet 52 and the oxidant outlet 54 of theembodiment of FIG. 1. FIG. 3a shows an embodiment of the fuel cell wherethe oxidant plenum 16 is entirely removed. In such an embodiment thecell would use the ambient environment as an oxidant supply. FIG. 3bshows an embodiment of the fuel cell where the fuel plenum 10 is removedentirely. In this configuration the fuel cell uses the ambientenvironment as a fuel supply.

FIG. 4 shows a first fuel cell 66 formed from a substrate 12 that ismade adjacent a second fuel cell 114 formed from a second substrate 62.The first and second fuel cells may be formed from either theassociation of multiple substrates or, as shown in FIG. 5, the firstfuel cell 66 and the second fuel cell 114 may be formed by creatingmultiple channels 14 within a single substrate 12.

In FIG. 4, a plurality of fuel cell structures are formed using separateporous substrates and they are then connected to each other at thesealant barriers 44 forming a fuel cell layer. In this figure a firstfuel cell 66 is connected to a second fuel cell 114. Multiple fuel cellscan be connected together in this manner to create a fuel cell layer 64with a fuel side 116 and an oxidant side 118. The details in the figurecan be easily understood by referring to the items numbers in thedescription of FIG. 1 and will therefore not be elaborated here.

In this embodiment it is envisioned that the fuel cell be connected inseries, in parallel or in combinations thereof to allow the fuel celllayer to produce current to drive an external load.

FIG. 4a shows a fuel cell layer with the fuel plenum open to the ambientenvironment. FIG. 4b shows a fuel cell layer with the oxidant plenumopen to the ambient environment. In this figure at least one optionalsupport member 26 is shown on at least one of the fuel cells.

FIG. 4c shows an embodiment of the fuel cell layer wherein up to 5000cells are connected together in the manner explained for FIG. 4.

In FIG. 5, the same fuel cell structures are formed in a single poroussubstrate 12. In this embodiment a plurality of fuel cells are createdwithin the porous substrate in the same manner as described for FIG. 1.Since, in this case, the fuel cells are formed within a single substratethe sealant barriers and electrical connections associated with eachfuel cell are not required. Instead a first sealant barrier 44 isdisposed on the first side of the porous substrate, a second sealantbarrier 46 is disposed on the second side of the porous substrate and aplurality of third sealant barriers 45 are disposed between the fuelcells. The sealant barriers provide gas impermeable separators betweenthe fuel cells within the fuel cell layer.

It is understood that the same embodiments shown for the multiplesubstrate structure in FIGS. 4a, 4b and 4c can be used with the singlesubstrate structure shown in FIG. 5.

This association of two fuel cells, either by the structure of FIG. 4 orthe structure of FIG. 5, can be extended to place an arbitrary number offuel cells in association with each other. In both embodiments, the endsof the multiple structures are sealed with a sealant barrier 44 and asecond sealant barrier 46. In both embodiments, negative electricalconnection 48 is attached on one end of the multiple fuel cell assemblyand positive electrical connection 50 is attached on the other end ofthe multiple fuel cell assembly to allow the multiple fuel cell assemblyto drive an external electrical load.

The association of multiple fuel cells produces a fuel cell layer 64having a fuel side 116 that is brought into association with a fuelplenum 10 and an oxidant side 118 that is brought into association withan oxidant plenum 16.

If the substrate material from which the fuel cells within the fuel celllayer 64 is formed is conductive, then electrical current produced bythe individual fuel cells is able to flow directly through the substratematerial and the sealant barriers 44 to create a bipolar fuel cellstructure within the formed fuel cell layer. If the substrate materialfrom which the fuel cells within the fuel cell layer are formed is notelectrically conductive than the first coating 34 and second coating 36should both be made of an electrically conducting material and formed sothat the first coating 34 is in electrical contact with the secondcatalyst layer 40 while second coating 36 is in electrical contact withthe first catalyst layer 38. The first coating 34 and the second coating36 are also made in electrical contact with the conductive sealantbarrier 44. In either case, with a conductive or non-conductivesubstrate the electrical current produced by the fuel cell can betransported to the positive and negative electrical connections.

An alternate configuration for the fuel cell layer is shown in FIG. 5a.In this configuration the first coating 34 is extended to connect theanode of the first fuel cell to the cathode of the second fuel cell. Thesecond coating 36 is likewise extended to contact the anode of the firstfuel cell. The first coating on the end of the second coating on the endcan be used to connect the fuel cells on the ends to the positiveelectrical connection 50 and the negative electrical connection 48. Inthis configuration portions of the first coating are porous to allowfuel to reach the anode and portions of the second coating are porous toallow oxidant to reach the cathode. In this configuration neither theporous substrate nor the sealant barrier need be electricallyconductive. It is also envisioned that only the first coating beextended to provide electrical contact between the cells or that onlythe second coating be extended to provide electrical contact between thecells.

When multiple fuel cells are formed into a fuel cell layer, as describedin FIGS. 4 and 5 a series electrical connection of the individual fuelcells results. The summed voltages of the multiple fuel cells produce apotential difference between the positive and negative electricalconnections at either end of the fuel cell layer. A larger number offuel cells will enable the fuel cell layer to produce a higher voltagebetween the electrical connections. Any combination of conductive ornon-conductive substrates, barriers and caps may be used so long as anelectrically conductive path between neighbouring anodes and cathodes iscreated. In this manner either an edge collected or preferably a bipolarseries electrical connection of each of the fuel cells in the fuel celllayer is achieved without the need to clamp distinct components togetherand without the use of independently formed layered components. Also,the direction of current flow in the fuel cell layer is overall in theplane of the fuel cell layer rather than being orthogonal to the fuelcell layer as is the case in most current designs. It is also envisionedto electrically connect the fuel cells within a fuel cell layer togetherin parallel or in a combination of series and parallel.

FIG. 6 is a cutaway perspective view of a fuel cell layer 64. In thisfigure a first fuel cell 66 is separated from a second fuel cell 114 bya sealant barrier 44. A third fuel cell 115 is separated from the secondfuel cell 114 by another sealant barrier 44. The layer has the samestructure as the layers described in FIGS. 4 and 5. The single fuel celllayer 64 can contain as many sealant barriers and cells as desired. Thedetermination of the spacing between individual fuel cells within thefell cell layer is at the discretion of the designer, limited bypragmatic issues of manufacturability and mass transport issues withinthe porous substrate.

The overall structure of the fuel cell layer 64 creates a seriesconnection of the individual fuel cells. Positive electrical connection50 and negative electrical connection 48 allow an external load to beconnected to the fuel cell layer, which produces a voltage that is amultiple of the single cell voltages produced within the fuel celllayer.

FIG. 7 shows a similar view as FIG. 6 of the fuel cell layer 64 but inthis Figure, each of the fuel cells 8 have a channel 14 with a lessstraight structure. Again, as with FIG. 6, FIG. 7 uses essentially thesame structure as shown in FIGS. 4 and 5, but repeated multiple timescreating a multi-cell structure. The less straight structure of thechannels allows for increased electrochemically active areas for theanodes and cathodes formed on the channel walls. The less straightchannels can be smoothly undulating or can be irregular in shaperesembling a fractral structured path which is known to have extremelyhigh area. Any arbitrary channel structure can be used with thisinvention allowing for the optimization of the area of the electrodes ineach fuel cell. A preferred embodiment includes a plurality of thinchannels that run parallel to each other and follow an irregular paththat folds back on itself in a manner suggestive of a fractal pattern.Another preferred embodiment of the invention includes at least onechannel that is in at least three planes.

FIG. 8 shows a perspective view of a cylindrical version 250 of amultiple fuel cell layer. In this version a multitude of non-planar fuelcells 208 are combined to create a fuel cell layer that encloses avolume 210. The enclosed volume 210 is used as the fuel plenum whileoxidant is supplied by the environment outside the cell. It is alsoenvisioned that the fuel be supplied by the environment outside thecylinder and that the enclosed volume 210 be used as an oxidant plenum.The cylindrical fuel cell 250 can either be constructed using a singleporous substrate which is in the shape of a cylinder using the methoddiscussed for combining cells in FIG. 5 or with multiple poroussubstrates that are brought together into a cylinder using the methoddiscussed for combining cells in FIG. 4.

FIG. 8a is a cross-section of a non-planar version of the fuel cell 208.The fuel cell has a fuel plenum 10 with fuel inlet 18 and fuel outlet 20and an oxidant plenum 16 with oxidant inlet 52 and oxidant outlet 54. Anon-planar porous substrate 212 is in communication with both the fuelplenum 10 and the oxidant plenum 16. A channel 14 is formed within thenon-planar porous substrate 212. The channel 14 has an anode 40 and acathode 38 constructed as described for FIG. 1 and is filled withelectrolyte 32. The fuel cell has a support member 26 a first coating 34and a second coating 36. The negative electrical connector 48 is shownadjacent sealant barrier 44. The positive electrical connector 50 isshown adjacent the optional sealant barrier 46. Although in this figurean arc is used to show the non-planar nature of the fuel cell, anyarbitrary configuration could be used. As with the fuel cells of FIG. 1the non-planar fuel cell can be combined to form a non-planar fuel celllayer with multiple cells and can be associated with fuel and optionaloxidant plenums of various configurations.

FIG. 9 shows a cross sectional view of a cylindrical version of a fuelcell. In this case the non-planar substrate 212 is shaped in the form ofa cylinder to enclose a volume 210. The fuel cell in this figure isshown with fuel 11 in the enclosed volume 210 providing fuel to the fuelcell. In this configuration the ambient environment outside the cellsupplies oxidant. It is also envisioned that oxidant be contained withinthe enclosed volume 210 and that the ambient environment supply thefuel.

FIG. 10 is another embodiment of a cylinder fuel cell 251 having thechannels 14 of the non-planar fuel cells 208 configured radially andorthogonal to the axis of the cylinder. It is understood that the fuelcells 208 within this figure can either be constructed or assembled, asdescribed for FIG. 4 or that they be formed within a single cylindricalsubstrate as described for FIG. 5.

FIG. 11 is another embodiment of a cylindrical fuel cell 252 having thechannel 14 of the non-planar fuel cell disposed in a wound or spiralfashion around the perimeter of the cylinder. Although, in this figure,only a single spiral channel 14 is shown, multiple fuel cells withmultiple channels could be formed using the porous substrate.

Although only cylindrical cells have been shown enclosing a volume it iscontemplated herein that shapes such as extruded rectangles, squares,ovals, triangles and other shapes as well as non-extruded shapes such ascones, pyramids, football shaped objects and other shapes that enclose avolume are included as part of the invention.

FIG. 12 is a cutaway perspective view of a bi-level fuel cell layerstructure 254 with two fuel cell layers, a first fuel cell layer 64 anda second fuel cell layer 112 each comprising an anode side and a cathodeside wherein the first fuel cell layer 64 is stacked on top of thesecond fuel cell layer 112 such that the anode side 264 of the firstfuel cell layer and the anode side 268 of the second fuel cell layeradjoin.

In this Figure, a seal 130 is disposed between the first and second fuelcell layer to form a fuel plenum 124. The two positive electricalconnections are connected to positive connector 120 and the two negativeelectrical connections are connected to negative connector 122 so thatthe individual fuel cell layers are now connected in an electricallyparallel configuration. The resulting assembly is a bi-level fuel celllayer structure 254 having a top 70 and a bottom 72, the top and bottombeing the cathode sides of the respective fuel cell layers. Theresulting structure is an enclosed plenum air breathing fuel cell thatachieves a series electrical connection of the individual fuel cells ineach fuel cell layer and a parallel electrical connection of the twofuel cell layers. Only fuel is required to be fed to the interior of thestructure and electrical current flows within the two fuel cell layersindependently of one another. There is no electrical connection betweenthe two fuel cell layers except at the parallel connection of thepositive and negative electrical connections at either end of the fuelcell layers in the structure.

An optional solid material with a flow field (not shown in this figure)can be disposed in the plenum 124 created by the first and second fuelcell layers 64, 112 and the seal 130. The plenum could also comprise apermeable material or a hydrogen storage material. Alternatelypressurized hydrogen or a liquid fuel could be stored within the plenum.It is also envisioned that the plenum be open to the ambientenvironment. The connectors can also be disposed in such a manner as toconnect the layers in series rather than in parallel. p FIG. 12a showsanother embodiment of a bi-level fuel cell layer structure 255 but inthis embodiment the fuel cell layers 64, 112 are place such that theircathode sides 266, 270 adjoin. In this embodiment oxidant is supplied tothe oxidant plenum 125 formed by the seal 130 and fuel is supplied tothe structure top 70 and bottom 72.

In FIG. 12a an optional solid material with a flow field 272 is shownwithin the plenum 125 created by the first and second fuel cell layers64, 112 and the seal 130. The plenum could also comprise a permeablematerial. It is also envisioned that the plenum be open to the ambientenvironment. The connectors can also be disposed in such a manner as toconnect the layers in series rather than in parallel.

Both configurations of the bi-level fuel cell layer structure form astand-alone electrical power-generating device with a parallelconnection of the two fuel cell layers doubling the power output of thestructure compared to the individual layers.

When reactant is delivered to the fuel cell structure from some externalsource and is flowed through the fuel cell layers it is desirable tocontrol the flow of the fuel over the fuel cell layer.

FIG. 13 shows an exploded cut-away view of a bi-level fuel cell layerstructure showing formed flow fields 68 within the fuel cell layers. Theseal is not shown in this figure to allow a better view of the formedflow fields 68. The formed flow fields can be created from a methodselected from the group comprising: cutting, ablating, molding,embossing, etching, laminating, embedding, melting, and combinationsthereof. The formed flow fields form a network of channels forcontrolling the distribution of reactant to the two fuel cell layers.Also, since the individual cells within each layer are oriented withtheir electrolyte and electrodes perpendicular to the surface of thelayer it is possible to form the flow fields into the surface withoutsignificantly reducing the active area of the fuel cells and withoutmodifying the overall structure of the fuel cell layer.

FIG. 14 shows a cross section of a bi-level fuel cell layer structurewith the seal 130 being as thin as possible to bring the fuel celllayers into physical but not electrical contact. Formed flow fields 68are shown in the surface of the fuel cell layers to allow reactants tobe delivered to the cell. The flow field 68 can take any path over thesurface of the fuel cell layers, providing a single path from an inletto an outlet, multiple parallel paths from inlet to outlet or single ormultiple paths from an inlet to a dead-end. The formed flow fields canbe disposed in the cathode or the anode side of the fuel cell layers.

FIG. 15 shows a multiple fuel cell layer structure 260. In thisstructure a first fuel cell layer 64 is stacked on a second fuel celllayer 112 such that the anode side 264 of the first fuel cell layer 64and the anode side 268 of the second fuel cell layer 112 adjoin. A thirdfuel cell layer 113 cathode side 276 adjoins the cathode side 270 of thesecond fuel cell layer 112 forming a stack with adjacent fuel celllayers. Additional layers can be disposed on the first, second and thirdfuel cell layers in a like manner. At least one seal 130 is disposedbetween adjacent fuel cell layers forming at least one plenum 124. Apositive connector 120 and a negative connector 122 are shown forconnecting the stack to an outside load allowing the current produced bythe fuel cell layers to power an external load.

FIG. 15a shows another embodiment of a multiple fuel cell layerstructure 260. In this structure a first fuel cell layer 64 is stackedon a second fuel cell layer 112 such that the cathode side 266 of thefirst fuel cell layer 64 and the cathode side 270 of the second fuelcell layer 112 adjoin. A third fuel cell layer 113 anode side 274adjoins the anode side 268 of the second fuel cell layer 112. Additionallayers can be disposed on the first, second and third fuel cell layersin a like manner. At least one seal 130 is disposed between two adjacentfuel cell layers forming at least one plenum 124. A positive connector120 and a negative connector 122 are shown for connecting the stack toan outside load allowing the current produced by the fuel cell layers topower an external load.

In both the FIG. 15 and the FIG. 15a embodiments the optional formedflow fields are shown on the fuel cell layers. Alternately, the at leastone plenum created by the at least one seal can be solid with a flowfield. The plenum can also comprise a permeable material. At least oneof the at least one plenums may be open to the ambient environment. Thefuel cell layers of the multiple fuel cell structure can be connected inseries, in parallel, or in combination thereof between the positive andnegative electrical connectors.

In the foregoing paragraphs a method of forming a fuel cell layerstructure by electrically connecting multiple fuel cell layers inparallel and by forming reactant distribution flow fields within theindividual fuel cell layers has been described. This configurationachieves the functionality of a conventional stack structure without therequirement for any explicit multi-function or bipolar separator plateto be inserted between discrete fuel cells or fuel cell layers resultingin an overall more space and material efficient design. Furthermore,since there is no current flow between neighbouring fuel cell layers thetask of sealing and connecting the fuel cell layers into the stack issimplified considerably. Forming the flow fields on the surface of thefuel cell layers allows the reactant distribution flow paths to beformed without significantly decreasing the total reactive area of thefuel cell stack in comparison to an embodiment constructed without theembossed flow fields. Extra volume for separate bipolar plates,separators, etc. is not required with this configuration providing anoverall increase in the volumetric power density of the fuel cell stack.

Although various materials could be used for the porous substrate of theinvention, one usable material could be a conductive material. Materialssuch as a metal foam, graphite, graphite composite, at least one siliconwafer, sintered polytetrafluoroethylene, crystalline polymers,composites of crystalline polymers, reinforced phenolic resin, carboncloth, carbon foam, carbon aerogel, ceramic, ceramic composites,composites of carbon and polymers, ceramic and glass composites,recycled organic materials, and combinations thereof are contemplated asusable in this invention.

The channel is contemplated to have up to 50 optional support membersseparating the walls of the channel. The support members can be locatedat the extreme ends of the channel, such as forming a top or bottom, orcan be located in the middle portion of the channel, or be oriented atan angle to the center of the channel. It is contemplated that thesupport member can be an insulating material. If an insulating materialis used, it is contemplated that silicon, graphite, graphite composite,polytetrafluoroethylene, polymethamethacrylate, crystalline polymers,crystalline copolymers, cross-linked polymers thereof, wood, andcombinations thereof can be usable in the invention.

Dimensionally, the channel can have a dimension ranging from 1 nanometerto 10 cm in height, 1 nanometer to 1 mm in width and from 1 nanometer to100 meters in length.

A single fuel cell of the invention, optionally within a fuel celllayer, is contemplated of being capable of producing betweenapproximately 0.25 volts and approximately 4 volts. Between 1 and 5000fuel cells are contemplated as usable in one fuel cell layer in thisdesign, however in a preferred embodiment, the fuel cell layer hasbetween 75 and 150 joined fuel cells. This fuel cell layer iscontemplated to be capable of producing a voltage between 0.25 volts and2500 volts. A fuel cell with more channels will be capable of producinghigher voltages.

The invention can be constructed such that the fuel comprises a memberof the group: pure hydrogen, gas containing hydrogen, formic acid, anaqueous solution comprising a member of the group: ammonia, methanol,ethanol and sodium borohydride, and combinations thereof. The inventioncan be constructed such that the oxidant comprises a member of thegroup: pure oxygen, gas containing oxygen, air, oxygen enriched air, andcombinations thereof.

Electrolyte usable in this invention can be a gel, a liquid or a solidmaterial. Various materials are contemplated as usable and include: aperfluoronated polymer containing sulphonic groups, an aqueous acidicsolution having a pH of at most 4, an aqueous alkaline solution having apH greater than 7, and combinations thereof. Additionally, it iscontemplated that the electrolyte layer can be between 1 nanometer and1.0 mm in thickness, or alternatively simply filling each undulatingchannel from first wall to second wall without a gap.

The fuel cell is manufactured using a first and second coating on theporous substrate. These coatings can be the same material or differentmaterials. At least one of the coatings can comprise a member of thegroup: polymer coating, epoxies, polytetrafluoro ethylene, polymethylmethacrylate, polyethylene, polypropylene, polybutylene, and copolymersthereof, cross-linked polymers thereof, conductive metal, andcombinations thereof. Alternatively, the first or second coating cancomprise a thin metallic layer such as a coating of gold, platinum,aluminum or tin as well as alloys of these or other metals or metalliccombinations.

The first and second catalyst layers that are contemplated as usable inthe invention can be a noble metal, alloys comprising noble metals,platinum, alloys of platinum, ruthenium, alloys of ruthenium, andcombinations of these materials. It is contemplated that ternary alloyshaving at least one noble metal are usable for good voltage creation.Platinum-ruthenium alloys are also contemplated as usable in thisinvention. The catalyst layers should each have a catalyst loadingquantity wherein the amount of catalyst may be different for each layer.

The material for the optional sealant barriers contemplated herein canbe selected from the group comprising: silicon, epoxy, polypropylene,polyethylene, polybutylene, and copolymers thereof, composites thereof,and combinations thereof.

One method for making the fuel cell contemplates the following steps:

-   -   a. forming a porous substrate having a top and bottom having a        first side and a second side;    -   b. coating at least a portion of the top with a first coating;    -   c. coating at least a portion of the bottom with a second        coating;    -   d. forming a channel using the porous substrate, wherein the        channel comprises a first channel wall and a second channel        wall;    -   e. forming an anode by depositing a first catalyst layer on the        first channel wall;    -   f. forming a cathode by depositing a second catalyst layer in        the second channel wall;    -   g. disposing electrolyte in at least a portion of the channel        contacting the anode and the cathode;    -   h. attaching a positive electrical connection on one end to the        first side of the porous substrate, and attaching a negative        electrical connection on one end to the second side of the        porous substrate;    -   i. attaching a fuel plenum to the porous substrate forming a        fuel cell;    -   j. attaching an oxidant plenum to the porous substrate;    -   k. disposing a sealant barrier around at least a portion of the        fuel cell; and    -   l. loading the fuel plenum with fuel and the oxidant plenum with        oxidant.

The sequence of operations described may be varied and steps combined asrequired to suit the particular material requirements and fabricationprocesses used. As well, the method can comprise forming between one and250 or more channels in the porous substrate.

Another method for forming a fuel cell envisioned in the inventioncontemplates the following steps:

-   -   a. repeating steps a through h of the method above as many times        as needed prior to joining the porous substrate to the fuel        plenum forming at least one additional fuel cell;    -   b. securing the porous substrate at the sealant barriers to at        least on additional fuel cell at its sealant barrier forming a        fuel cell layer and extending the fuel cell layer securing        additional formed fuel cells to the fuel cell layer at        respective sealant barriers;    -   c. attaching the positive electrical connections and the        negative electrical connections of the fuel cell layer together;    -   d. attaching the joined fuel cells to the fuel plenum; and    -   e. attaching the joined fuel cells to the oxidant plenum.

The positive electrical connections and the negative electricalconnections of the fuel cells within the fuel cell layer can beconnected in series, in parallel or in a combination of series andparallel.

Yet another method for making a fuel cell layer is contemplated whichhas the steps of:

-   -   a. forming a porous substrate comprising a top and bottom, a        first side and a second side;    -   b. coating at least a portion of the top with a first coating;    -   c. coating at least a portion of the bottom with a second        coating;    -   d. forming a plurality of distinct channels using the porous        substrate, wherein each distinct channel comprises a first        channel wall and a second channel wall;    -   e. forming a plurality of anodes by depositing a plurality of        first catalyst layers on the first channel walls;    -   f. forming a plurality of cathodes by depositing a plurality of        second catalyst layers in the second channel walls;    -   g. disposing electrolyte in at least a portion of each distinct        channel;    -   h. disposing a first sealant barrier on at least a portion of        the first side;    -   i. disposing a second sealant barrier on at least a portion of        the second side;    -   j. forming a plurality of third sealant barriers between each of        the distinct channels creating a plurality of independent fuel        cells adjacent each other in the porous substrate;    -   k. attaching a positive electrical connection to the first side        of the porous substrate;    -   l. attaching a negative electrical connection to the second side        of the porous substrate;    -   m. attaching a fuel cell positive electrical connection to each        independent fuel cells    -   n. attaching a fuel cell negative electrical connection to each        independent fuel cell forming a fuel cell layer; and    -   o. disposing a sealant barrier around at least a portion of the        fuel cell layer.

In any of the methods described above a number of different methods offorming the porous substrate are contemplated herein. The poroussubstrate can be formed by a method that is a member of the groupcomprising: casting and then baking, slicing layers from a pre-formedbrick, molding, extruding, and combinations thereof. The formed poroussubstrate may be non-planar or enclose a volume.

If at least one of the coatings is deposited with thin film depositiontechniques, the technique may include a member of the group comprising:sputtering, electroless plating, electroplating, soldering, physicalvapor deposition, chemical vapor deposition. If at least one of thecoatings is an epoxy coating the coating can be disposed on thesubstrate by a method selected from the group: screen printing, ink jetprinting, spreading with a spatula, spray gun deposition, vacuum baggingand combinations thereof. A mask can be used when applying the coatingsto the porous substrate. If required, a portion of the coating can beremoved prior to adding the electrolyte.

The channel can be formed in the porous substrate by a method selectedfrom the group comprising: embossing, ablating, etching, extruding,laminating, embedding, melting, molding, cutting, and combinationsthereof. If etching is used, the etching can be by a method selectedfrom the group comprising: laser etching, deep reactive ion etching, andalkaline etching. Alternatively, it is anticipated the channels can beformed by micro-milling using laser cutting, high pressure water jets,micro-dimensioned rotary tools or mechanical dicing saws.

Within the invention it is envisioned to deposit the electrolyte in thechannel using a method that is a member of the group comprising:pressure injection, vacuum forming, hot embossing, and combinationsthereof.

The variations for making the apparatus can be implemented into any ofthe methods described above. For example, the method can contemplateusing a conductive material for the sealant barrier and/or an insulationmaterial for the support member.

The fuel cell of the invention can be used by first, connecting a fuelsource to a fuel plenum inlet; second, connecting a fuel plenum outletto a re-circulating controller; third, connecting an oxidant plenuminlet to an oxidant source; fourth, connecting an oxidant plenum outletto a flow control system, fifth, connecting a positive electricalconnection and a negative electrical connection to an external load;sixth, flowing fuel and oxidant to the inlets; and finally, driving loadwith electricity produced by the fuel cell.

If a dead-ended version of the fuel cell is used the operation is muchsimpler. First, the fuel inlet is connected to a fuel supply, second,the oxidant inlet is connected to an oxidant supply, third, the positiveelectrical connection and the negative electrical connection areconnected to an external load; and finally, the load is driven withelectricity produced by the fuel cell.

The method of the invention can further comprise the step of sealing theplenum outlets and inlets after the fuel and oxidant is loaded intotheir respective plenums creating a dead ended fuel cell. The fuel cellcan then be connected to an external load using the positive andnegative electrical connections and used to drive the external load.

It is envisioned within this invention to use any combination of fueland oxidant inlets and outlets to operate the fuel cell.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention.

1. A multiple fuel cell layer structure comprising: a. a plurality oflayers of fuel cells, each layer of fuel cells comprising an anode sideand a cathode side, a positive end and a negative end, and wherein afirst layer of fuel cells is stacked on top of a second layer of fuelcells such that the anode side of the first layer of fuel cells and theanode side of the second layer of fuel cells adjoin, a third layer offuel cells is stacked on the second layer of fuel cells such that thethird layer of fuel cells cathode side adjoins the second layer of fuelcells cathode side forming a stack with adjacent layers of fuel cells,additional layers of fuel cells can then be disposed on said first,second, and third layers of fuel cells in a like manner; b. at least oneseal disposed between said adjacent layers of fuel cells forming atleast one plenum; c. a positive connector for said stack to an outsideload; and d. a negative connector for connecting said stack to saidoutside load; such that when fuel is presented to the anode sides of theplurality of said layers, and oxidant is presented to the cathode sidesof the plurality of said layers current is produced to drive saidoutside load.
 2. The multiple fuel cell layer structure of claim 1,wherein said at least one plenum is a member of the group: fuel plenum,an oxidant plenum and combinations thereof.
 3. The multiple fuel celllayer structure of claim 1, wherein said at least one plenum is apermeable material.
 4. The multiple fuel cell layer structure of claim1, wherein said at least one plenum is a solid material with a flowfield.
 5. The multiple fuel cell layer structure of claim 1, whereinsaid at least one plenum is open to an ambient environment.
 6. Themultiple fuel cell layer structure of claim 1, wherein said positive andnegative ends are connected in series between the positive and negativeconnectors.
 7. The multiple fuel cell layer structure of claim 1,wherein said positive ends and negative ends are connected in parallelto the positive and negative connectors.
 8. The multiple fuel cell layerstructure of claim 1, wherein said positive ends and said negative endsare connected in a combination of in series and in parallel between thepositive and negative connectors.
 9. A multiple fuel cell layerstructure comprising: a. a plurality of layers of fuel cells, each layerof fuel cells comprising an anode side and a cathode side, a positiveend and a negative end, and wherein a first layer of fuel cells isstacked on top of a second layer of fuel cells such that the anode sideof the first layer of fuel cells and the anode side of the second layerof fuel cells adjoin, a third layer of fuel cells is stacked on thesecond layer of fuel cells such that the third layer of fuel cellscathode side adjoins the second layer of fuel cells cathode side forminga stack with adjacent layers of fuel cells, additional layers of fuelcells can then be disposed on said first, second and third layers offuel cells in a like manner; b. at least one seal disposed between saidadjacent layers of fuel cells forming at least one plenum; c. at leastone flowfield is formed in at least one of said layer of said stack; d.a positive connector for connecting said stack to an outside load; ande. a negative connector for connecting said stack to said outside load;such that when fuel is presented to the anode sides of the plurality oflayers of fuel cells, and oxidant is presented to the cathode sides ofthe plurality of layers of fuel cells current is produced to drive saidoutside load.
 10. The multiple fuel cell layer structure of claim 9,wherein said at least one plenum is a member of the group consisting offuel plenum, an oxidant plenum and combinations thereof.
 11. Themultiple fuel cell layer structure of claim 9, wherein said at least oneplenum is a permeable material.
 12. The multiple fuel cell layerstructure of claim 9, wherein said at least one plenum is a solidmaterial with a flow field.
 13. The multiple fuel cell layer structureof claim 9, wherein said at least one plenum is open to an ambientenvironment.
 14. The multiple fuel cell layer structure of claim 9,wherein said positive and negative ends are connected in series betweenthe positive and negative connectors.
 15. The multiple fuel cell layerstructure of claim 9, wherein said positive ends and negative ends areconnected in parallel to the positive and negative connectors.
 16. Themultiple fuel cell layer structure of claim 9, wherein said positiveends and said negative ends are connected in a combination of in seriesand in parallel between the positive and negative connectors.
 17. Themultiple fuel cell layer structure of claim 9, wherein said flowfield isformed by a method selected from the group consisting of cutting,ablating, molding, embossing, etching, laminating, embedding, meltingand combinations thereof.
 18. A bi-level fuel cell layer structurecomprising: a. a first fuel cell layer and a second fuel cell layerslayer, each fuel cell layer operating with diffusion of reactant from ananode side to a cathode side, and further comprising, a positive end anda negative end, and wherein said first fuel cell layer is stacked on topof said second fuel cell layer such that the anode side of the firstfuel cell layer and the anode side of the second fuel cell layer adjoinforming a bi-level stack; b. a seal disposed between said first andsecond fuel cell layers forming a fuel plenum; c. a positive connectorfor connecting said bi-level stack to an outside load; and d. a negativeconnector for connecting said bi-level stack to said outside load; suchthat when fuel is introduced to the fuel plenum and the cathode sidesare exposed to an oxidant, current is produced to drive said outsideload.
 19. The bi-level fuel cell layer structure of claim 18, whereinsaid fuel plenum is a permeable material.
 20. The bi-level fuel celllayer structure of claim 18, wherein said fuel plenum is a solidmaterial with a flow field.
 21. The bi-level fuel cell layer structureof claim 18, wherein said fuel plenum is open to an ambient environment.22. The bi-level fuel cell layer structure of claim 18, wherein saidpositive and negative ends are connected in series between the positiveand negative connectors.
 23. The bi-level fuel cell layer structure ofclaim 18, wherein said positive ends and negative ends are connected inparallel to the positive and negative connectors.
 24. The bi-level fuelcell layer structure of claim 18, wherein said fuel plenum comprises avolume comprising a hydrogen storage material.
 25. The bi-level fuelcell layer structure of claim 18, further comprising at least oneflowfield formed in at least one fuel cell layer.
 26. The bi-level fuelcell layer structure of claim 25, wherein said flowfield is formed by amethod selected from the group consisting of cutting, ablating, molding,embossing, etching, laminating, embedding, melting and combinationsthereof.
 27. A bi-level fuel cell layer structure comprising: a cellfirst layer of fuel cells and a second layer of fuel cells, each fuelcell comprising an anode side and a cathode side, a positive end and anegative end, and wherein said first fuel cell layer is stacked on topof said second fuel cell layer such that the cathode side of the firstfuel cell layer and the cathode side of the second fuel cell layeradjoin forming a bi-level stack; a seal disposed between said first andsecond fuel cell layer forming a oxidant plenum; a positive connectorfor connecting said bi-level stack to an outside load; and a negativeconnector for connecting said bi-level stack to said outside load; suchthat when oxidant is introduced to the oxidant plenum and the anodesides are exposed to a fuel, current is produced to drive said outsideload.
 28. The bi-level fuel cell layer structure of claim 27, whereinsaid oxidant plenum is a permeable material.
 29. The bi-level fuel celllayer structure of claim 27, wherein said oxidant plenum is a solidmaterial with a flow field.
 30. The bi-level fuel cell layer structureof claim 27, wherein said oxidant plenum is open to an ambientenvironment.
 31. The bi-level fuel cell layer structure of claim 27,wherein said positive and negative ends are connected in series betweenthe positive and negative connectors.
 32. The bi-level fuel cell layerstructure of claim 27, wherein said positive ends and negative ends areconnected in parallel to the positive and negative connectors.
 33. Thebi-level fuel cell layer structure of claim 27, further comprising atleast one flowfield formed in at least one fuel cell layer.
 34. Thebi-level fuel cell layer structure of claim 33, wherein said flowfieldis formed by a method selected from the group consisting of cutting,ablating, molding, embossing, etching, laminating, embedding, meltingand combinations thereof.
 35. A bi-level fuel cell layer structure,comprising: a first fuel cell layer and a second fuel cell layer, eachfuel cell layer comprising: a plurality of fuel cell units comprising:an electrolyte disposed in a channel formed in a substrate; one or moreconductive sealant barriers, positioned to provide gas impermeableseparation between adjacent fuel cell units; a first coating, in contactwith the electrolyte and the one or more conductive sealant barriers; asecond coating, in contact with the electrolyte and the one or moreconductive sealant barriers; a positive end and a negative end; a sealin contact with the first fuel cell layer and second fuel cell layer andpositioned to form a reactant plenum; a positive connector and negativeconnector, each in contact with an outside load; wherein the first fuelcell layer and second fuel cell layer are in contact such that thereactant plenum is utilized by like coatings of each fuel cell layer andwherein the negative ends of each fuel cell layer are in electricalcontact sufficient to form a bi-level structure.
 36. The bi-level fuelcell layer structure of claim 35 , wherein the first and second coatingscomprise thin metallic layers.
 37. The bi-level fuel cell layerstructure of claim 35 , wherein the first and second coatings compriseplatinum.
 38. The bi-level fuel cell layer structure of claim 35 ,further comprising a conductive substrate positioned between adjacentfuel cell units to facilitate a current flow between the fuel cellunits.
 39. The bi-level fuel cell layer structure of claim 35 , furthercomprising a fuel within the reactant plenum.
 40. The bi-level fuel celllayer structure of claim 39 , wherein the fuel comprises hydrogen. 41.The bi-level fuel cell layer structure of claim 35 , further comprisingan oxidant within the reactant plenum.
 42. A bi-level fuel cell layerstructure, comprising: a first fuel cell layer and a second fuel celllayer, each fuel cell layer comprising: a plurality of fuel cell units,each said fuel cell unit comprising: a substrate having a channel formedtherein, the channel defined by first and second walls; an electrolytedisposed in the channel; a first catalyst layer disposed on the firstwall; a second catalyst layer disposed on the second wall; one or moreconductive sealant barriers positioned to provide gas impermeableseparation between adjacent fuel cell units; a positive end and anegative end; a seal in contact with the first fuel cell layer andsecond fuel cell layer and positioned to form a reactant plenum; apositive connector and negative connector, each in contact with anoutside load; wherein the first fuel cell layer and second fuel celllayer are in contact such that the reactant plenum is utilized by likecatalyst layers of each fuel cell layer and wherein the negative ends ofeach fuel cell layer are in electrical contact sufficient to form abi-level structure.
 43. The bi-level fuel cell layer structure of claim42 , wherein the first and second catalyst layers comprise thin metalliclayers.
 44. The bi-level fuel cell layer structure of claim 42 , whereinthe first and second catalyst layers comprise platinum.
 45. The bi-levelfuel cell layer structure of claim 42 , further comprising a fuel withinthe reactant plenum.
 46. The bi-level fuel cell layer structure of claim42 , wherein the fuel comprises hydrogen.
 47. The bi-level fuel celllayer structure of claim 42 , further comprising an oxidant within thereactant plenum.
 48. The bi-level fuel cell layer structure of claim 42, further comprising a solid material with a flowfield within thereactant plenum.
 49. The bi-level fuel cell layer structure of claim 42, wherein the reactant plenum is open to an ambient environment.
 50. Thebi-level fuel cell layer structure of claim 42 , wherein the positiveand negative ends of the fuel cell layers are connected in seriesbetween the positive and negative connectors.
 51. The bi-level fuel celllayer structure of claim 42 , wherein the positive ends and negativeends of the fuel cell layers are connected in parallel to the positiveand negative connectors.
 52. The bi-level fuel cell layer structure ofclaim 42 , further comprising a hydrogen storage material within thereactant plenum.
 53. The bi-level fuel cell layer structure of claim 42, further comprising at least one flowfield formed in at least one fuelcell layer.
 54. The bi-level fuel cell layer structure of claim 53 ,wherein the flowfield is formed by a method selected from the groupconsisting of cutting, ablating, molding, embossing, etching,laminating, embedding, melting and combinations thereof.
 55. A multiplelayer fuel cell structure, comprising: a first fuel cell layer and asecond fuel cell layer, said first and second fuel cell layers arrangedvertically with respect to one another, each fuel cell layer comprising:a plurality of fuel cell units arranged laterally with respect to oneanother, each fuel cell unit comprising: at least one substrate definingfirst and second walls in spaced relation to one another, the first andsecond walls defining a channel; a first catalyst layer disposed on thefirst wall; a second catalyst layer disposed on the second wall; anelectrolyte disposed in the channel between the first and second walls,whereby said first wall forms an anode and said second wall forms acathode of said fuel cell unit; at least one sealant barrier, at leastone such sealant barrier placed between laterally adjacent fuel cellunits, and configured to provide gas impermeable separation between suchadjacent fuel cell units; and a positive connector and negativeconnector, each configured for contacting an outside load; a firstenclosure configured to form a first reactant plenum, said firstenclosure in fluid communication with each of said first and secondvertically arranged fuel cell layers and further in fluid communicationwith each fuel cell unit in each said layer; a first electricalconnection formed connecting said positive connectors of said first andsecond fuel cell layers; and a second electrical connection formedconnecting said negative connectors of said first and second fuel celllayers.
 56. The multiple layer fuel cell structure of claim 55, whereinsaid first enclosure is placed vertically between said first and secondfuel cell layers.
 57. The multiple layer fuel cell structure of claim55, further comprising a second enclosure configured to form a secondreactant plenum, said second enclosure in fluid communication with eachof said first and second vertically arranged fuel cell layers and witheach fuel cell unit in each said layer.
 58. The multiple layer fuel cellstructure of claim 55, wherein a plurality of fuel cell units withineach fuel cell layer are electrically coupled in series within saidlayer.
 59. A method of making a multiple level fuel cell structure,comprising the acts of: forming a first fuel cell layer, comprising,forming a plurality of fuel cell units, each fuel cell unit comprising avolume of electrolyte, and further comprising an anode and a cathodecoupled to opposing sides of said volume of electrolyte; forming asealant barrier between each fuel cell unit and a laterally adjacentfuel cell unit; and forming an electrical connection between each fuelcell unit and at least one adjacent fuel cell unit in said first fuelcell layer, comprising forming a connection between the anode of onesuch fuel cell unit and the cathode of the adjacent fuel cell unit;forming a positive contact for said first fuel cell layer; and forming anegative contact for said first fuel cell layer; forming a second fuelcell layer, said second fuel cell layer vertically disposed relative tosaid first fuel cell layer, comprising, forming a plurality of fuel cellunits, each fuel cell unit comprising a volume of electrolyte, andfurther comprising an anode and a cathode coupled to opposing sides ofsaid volume of electrolyte; forming a sealant barrier between each fuelcell unit and a laterally adjacent fuel cell unit in said second fuelcell layer; and forming an electrical connection between each fuel cellunit and at least one adjacent fuel cell unit in said second fuel celllayer, comprising forming a connection between the anode of one suchfuel cell unit and the cathode of the adjacent fuel cell unit; forming apositive contact for said second fuel cell layer; and forming a negativecontact for said second fuel cell layer; forming a first reactantplenum, said reactant plenum in fluid communication with each fuel cellin said first and second fuel cell layers; forming a first electricalconnection between said positive contacts of said first and second fuelcell layers; and forming a second electrical connection between saidnegative contacts of said first and second fuel cell layers.
 60. Themethod of making a multiple level fuel cell structure of claim 59,wherein said first reactant plenum is placed vertically between saidfirst and second fuel cell layers.
 61. The method of making a multiplelevel fuel cell structure of claim 59, further comprising the act offorming a second reactant plenum, said reactant plenum in fluidcommunication with each fuel cell in said first and second fuel celllayers.
 62. The method of claim 61, further comprising the acts of:introducing a fuel into one of said first and second reactant plenums;and introducing an oxidant into the other of said first and secondreactant plenums.
 63. A method of making a bi-level fuel cell layerstructure, comprising the acts of: forming first and second fuel celllayers, each fuel cell layer formed through acts comprising, forming asubstrate having a first side and second side; coating at least aportion of the first side with a first coating; coating at least aportion of the second side with a second coating; forming a channel inthe substrate, including a first channel wall and second channel wall;forming an anode by depositing a first catalyst layer on the firstchannel wall; forming a cathode by depositing a second catalyst layer onthe second channel wall; disposing electrolyte in at least a portion ofthe channel in contact with the anode and cathode; contacting a positiveelectrical connection on one end to the first side of the substrate;contacting a negative electrical connection on one end to the secondside of the substrate, sufficient to form a fuel cell unit; disposing asealant barrier around at least a portion of the fuel cell unit; forminga first reactant plenum; and placing said first reactant plenum incontact with a first side of the first fuel cell layer and a first sideof the second fuel cell layer, to form a bi-level structure wherein thefirst reactant plenum is utilized by like electrodes of the first fuelcell layer and second fuel cell layer.